[Kenwood] TS-940S PLL Trouble

[Michael Tope]

Hi All,

I have a late model TS-940S (S/N 904xxxx) which has a
problem with frequency display blanking (and corresponding
receive audio cutout) which if I understand correctly is an
indication that one of the rig's PLLs is unlocking. Originally,
when the problem occured, the frequency display would blink
alternating between all dots and the displayed frequency.
Thinking I had a faulty ROM socket, I went down that path a
soldered IC2 directly to the digital board. This didn't cure the
problem, it just changed it. Now when the receiver cuts out,
the display goes to all dots and just stays that way (as opposed
to alternating between dots and alphanumeric). The problem
comes and goes and doesn't appear to correlate with any
external stimulus. I poked around the digital board and the
PLL unit and couldn't find any obvious loose connection or
mechanically sensitive points which would induce the failure
when stimulated. Wiggling and twisting the chassis with the
covers off (to put a little twist in the PC boards) doesn't seem
to do anything either.

Any suggestions for what might be causing this? The radio
works fine otherwise, but isn't much good for anything since it
can cut out without warning.

Thanks,

Mike, W4EF......................................................